Earthworm is an animal that everyone is very familiar with. Many people like to call the Earthworm Qufu, or the Earth Dragon. Its body is composed of many similar body segments and belongs to the annelid.
Earthworm is “an animal with several hearts.” As we all know, the heart is the center of the circulatory system of higher animals and humans, and it is also the engine of blood flow, but there is only one heart in higher animals and humans.
Why does Earthworm have several hearts? Of course, the heart of Earthworm is different from the heart of higher animals. It is actually an enlarged circular blood vessel.
In lower animals, an animal like the Earthworm has several hearts. For the more common Eyeworm, the Earthworm has a large blood vessel on the back and abdomen. There are four pairs of enlarged ring vessels connected in the middle. These ring vessels can rhythmically beat.
By beating, blood can be circulated throughout the body. People call these four pairs of blood vessels “four pairs of hearts.” Because of the wide variety of Earthworms, not all Earthworms have several hearts. Some Earthworms have only one heart, and some Earthworms have five pairs of hearts.
There are more than 2,500 kinds of Earthworms in the world, which are widely distributed, and they are also found in extremely cold snow and ice.